Medial collateral ligament

Embryologically and phylogenically, the ligament represents the distal portion of the tendon of adductor magnus muscle. In lower animals, adductor magnus inserts into the tibia. Because of this, the ligament occasionally contains muscle fibres. This is an atavistic variation.

An MCL injury can be very painful and is caused by a valgus stress to a slightly bent knee, often when landing, bending or on high impact. It may be difficult to apply pressure on the injured leg for at least a few days. It can be caused by a direct blow to lateral side of knee. The most common knee structure damaged in skiing is the medial collateral ligament, although the carve turn has diminished the incidence somewhat.[1] MCL strains and tears are also fairly common in American football. The center and the guards are the most common victims of this type of injury due to the grip trend on their cleats, although sometimes it can be caused by a helmet striking the knee. The number of football players who get this injury has increased in recent years. Companies are currently trying to develop better cleats that will prevent the injury. MCL is also crucially affected in breaststroke and many professional swimmers suffer from chronic MCL pains.

There are three distinct levels in a MCL injury. Grade 1 is a minor sprain, grade 2 in a major sprain or a minor tear, and grade 3 is a major tear. Based on the grade of the injury treatment options will vary.[2]

Depending on the grade of the injury, the lowest grade (grade 1) can take between 2 and 10 weeks for the injury to fully heal. Recovery times for grades 2 and 3 can take several weeks to several months.

Treatment of a partial tear or stretch injury is usually conservative. Sports medicine therapists should be a first choice option for diagnosis and treatment of injuries to this structure. This includes measures to control inflammation as well as bracing. Kannus has shown good clinical results with conservative care of grade II sprains, but poor results in grade III sprains.[3] As a result, more severe grade III and IV injuries to the MCL that lead to ongoing instability may require arthroscopic surgery. However, the medical literature considers surgery for most MCL injuries to be controversial.[4] Isolated MCL sprains are common.

For higher grade tears of the MCL with ongoing instability, the MCL can be sutured or replaced. Other non-surgical approaches for more severe MCL injuries may include prolotherapy, which has been shown by Reeves in a small RCT to reduce translation on KT-1000 arthrometer versus placebo.[5] The future of non-surgical care for a non-healing MCL injury with laxity (partial ligament tear) is likely bioengineering. Fan et al. (2008) have demonstrated that knee ligament reconstruction is possible using mesenchymal stem cells and a silk scaffold.[6]